Yarn clamping and severing mechanism for knitting machines



V. T. STACK Sept. 25, 1962 YARN CLAMPING AND SEVERING MECHANISM FOR KNITTING MACHINES 5 Sheets-Sheet 1 Filed June 13, 1956 INVENTOR. 1 2/7701; I]? Szac/i',

BY 621x621 ATTORNEYS V. T. STACK Sept. 25, 1962 YARN CLAMPING AND SEVERING MECHANISM FOR KNITTING MACHINES Filed June 15, 1956 5 Sheets-Sheet 2 INVENTOR.

ATTORNEYS Yer/7017 T yaw/10m I mlml Sept. 25, 1962 v STACK 3,055,199

YARN CLAMPING AND SEVERING MECHANISM FOR KNITTING MACHINES Filed June 13, 1956 5 Sheets-Sheet 3 6 T 6 FIG: 4 37 .FIG': 5 30 if? I 3 5 25 [76 5 6 54 Z 5 W w .31

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A TTORNEYS Sept. 25, 1962 v. T. STACK 3,055,199

YARN CLAMPING AND SEVERING MECHANISM FOR KNITTING MACHINES Filed June 15, 1956 5 Sheets-Sheet 4 IIHH H 1 %j 6 6 FIG: 10- HG 11- 37 BF E9 30 B9 30 36 3 h H6 3 I, 4

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A TTORNEYS Sept. 25, 1962 v. T. STACK 3,055,199

YARN CLAMPING AND SEVERING MECHANISM FOR KNITTING MACHINES Filed June 13, 1956 5 Sheets-Sheet 5 IN VEN TOR.

A TTORNEYS United States Patent 3,055,199 YARN CLAMPING AND SEVERING MECHANISM FOR KNITTING MACHINES Vernon T. Stack, Winston-Salem, N.C., assignor, by mesne assignments, to The Gordon Company, Winston-Salem,

N.C., a partnership Filed June 13, 1956, Ser. No. 591,229 13 Claims. (Cl. 66140) This invention relates to yarn clamping and severing mechanism for knitting machines. More particularly it is concerned with yarn clamping and severing mechanism for circular knitting machines used in the commercial production of seamless hosiery including welt top ladies stockings. In the knitting of such hosiery, it is customary to form different parts of the stockings from yarns of different weights or deniers.

With the usual forms of clamping and severing mechanisms, yarn ends of considerable length are left attached to the fabric of the stockings at the insides thereof incident to yarn changes. To remove these trailing yarn ends, it has been necessary to separately handle the stockings after delivery from the machines, which operation added materially to the costs of production.

The chief aim of my invention is to obviate the above drawback. This objective is realized in practice, as hereinafter more fully disclosed, through provision of a simple and reliable automatically operable clamping and severing mechanism by which, as the yarn changes are made, the long trailing ends of the outgoing yarns are cut off close to the fabric, and the segments so severed are removed from the clamp elements of the mechanism and conveyed to a collecting receiver.

A further object of my invention is to secure the foregoing advantages in a clamping and severing mechanism in the form of an attachment capable of ready application to standard circular knitting machines without necessitating any alteration in the construction or normal mode of operation of such machines.

Other objects and attendant advantages will appear from the following detailed description of the attached drawings, wherein:

FIG. 1 is a fragmentary view in perspective showing a yarn clamping and severing mechanism, conveniently embodying my invention in one form, in association with a circular stocking knitting machine.

FIG. 2 is a fragmentary detail view in vertical section taken as indicated by the angled arrows IIII in FIG. 1 and drawn to a larger scale.

FIG. 3 is a fragmentary detail view in horizontal section taken as indicated by the angled arrows TIL-III in FIG. 2.

FIGS. 4-7 are perspective views similar to FIG. 1 showing successive steps in the operation of the mechanism incident to Withdrawal of a yarn from the knitting.

FIGS. 811 are views similar in turn to FIGS. 4-7 showing successive steps in the operation of the mechanism during introduction of the yarn into the knitting.

FIG. 12 is a view similar to FIG. 1 showing a modified form of the mechanism.

FIG. 13 shows an alternative form of means for disposing of the severed segments of the yarn.

FIGS. 14 and 15 are detail views in section taken as indicated by the angled arrows XIV--XIV and XV-XV respectively in FIG. 13 and drawn to a larger scale.

FIGS. 16, 17 and 18 show successive steps in the operation of still another alternative form of means for dis posing of the severed yarn segments.

For convenience of exemplification herein, I have illustrated my improved yarn clamping and severing mechanism as associated with a circular knitting machine of the well known Scott and Williams model K type constructed generally in accordance with U.S. Patents Nos.

3,ii55,l99 Patented Sept. 25, 1962 "ice 1,148,055 and 1,282,958 granted to Robert W. Scott on July 27, 1915, and October 29, 1918, respectively, only those parts of the machine deemed necessary to the understanding of my invention being illustrated.

With more specific reference first more particularly to FIGS. l-ll of these drawings, the rotary cylinder of the knitting machine is indicated at 1 and the needles carried thereby at 2; the usual latch guard ring at 3; one of the usual pivoted upwardly-retractable yarn feed fingers at 4; and the usual dial cap or disk at 5 of which the outside transfer cam is indicated at 13 in FIG. 2, said disk being station-arily supported axially of the upper end of the needle cylinder from above by the pendant boss 6 of a fixed bracket, not shown.

The form of yarn severing mechanism of my invention comprises in this instance, a cutting wheel 8 which is located substantially diametrically opposite the yarn finger 4, said cutting Wheel being afiixed to the lower end of a vertical drive shaft 9 which extends through and is free to rotate in a bearing 10 (FIG. 2) secured tothe dial cap 5. It will be noted from FIGS. 2 and 3 that the cutting wheel 8 is so arranged that its sharp edged teeth sweep slightly outward beyond the peripheral edge of the dial cap 5 into close proximity to the circle of the knitting needles 2 to shear against the knife edge 11 of a stationary cutting blade 12 recessed into the under side of said cap. -In this instance, the shaft 9 of the cutting wheel 8 is driven by an electric motor 15 fixedly supported from the bearing 6 and supplied with current from a power line designated 16 in FIG. 2. A switch 17 interposed in the power line 16 is arranged to be controlled and operated, through a finger 18, by high links, such as shown at 19, on the usual intermittently progressed measuring chain 20 of the knitting machine.

The mechanism of my invention further includes a yarn restraining or tensioning element 25 which is fashioned from relatively thin sheet metal, the same being fixedly secured by a screw 26 upon a slightly raised embossment 24 of the disk 5 with the major portion thereof overhanging the main surface of said disk. -As shown, the element 25 has a guide tongue 27 which is curved con centrically to the axis of the needle cylinder 1 and is rounded upwardly toward the yarn finger 4. \Fixedly secured by a screw 29, to the main surface of the dial cap or disk 5 in the interval between the yarn finger 4 and the yarn restraining element 25 is a yarn clamping element 30 of which the free end is upturned and extends outwardly crosswise over the tongue 27 of said yarn restraining element 25. Pivoted on an upstanding lug -3-1 on the disk 5 is a yarn clamping finger 32 which, it is to be understood, is operated as in Patent 1,148,055 hereinbefore referred to, and which normally bears upon the basal portion of the yarn restraining element 25.

For the purpose of disposing the segments of the yarn severed by the cutting wheel 8 during insertions and retractions of the feeding finger 4, as later on explained, I have provided a horizontally arranged tube 40 which is connected to a source of compressed air (not illustrated), and which extends crosswise over the disk 5 and discharges into a catch basket 41 of wire mesh or the like supported by a bracket 42 from the latch guard ring 3. As shown, the tube 40 has an open-ended downward branch 43 which reaches into close proximity to the edge of the bight in the basal portion of the yarn restraining element 25. Tube 40 and branch 43 function as an aspirator.

Operation Incident to Yarn Withdrawal In FIG. 4, the finger 4 is shown in lowered position feeding the yarn Y to the needles in the normal well known way. In FIG. 5, the finger 4 has been raised out of action, the last of the needles to be fed being desig nated 2'. As the cylinder 1 continues in its rotation, the yarn Y is directed downwardly by the upturned end of the clamping element 30 to pass over the restraining element 25 as in FIG. 5 until caught beneath said clamp element, the movable clamp finger 32 being raised at this time. As the cylinder v1 continues further in its rotation, the clamp finger 32 is lowered to hold the yarn just as the latter reaches the rotary cutter 8 and is severed as shown in FIG. 7. It is to be noted from FIGS. 2 and 3, that the angle of incidence of the yarn relative to the needles changes as the yarn is pulled around the edge of the outside transfer cam 13 by the rotation of the cylinder 1, three successive angular positions being indicated. The yarn is eventually caught by one of the blades of the cutting wheel 8 and is brought to vertical position as such cutting wheel blade meets with the fixed blade 12 to effect the severing. Thus, due to the location of the cutting Wheel 8 at the bottom of the outside transfer cam 13 is adjacent the periphery of the disk '5, the yarn is severed very close to the fabric so that but a short negligible end is left projecting from the fabric at the inside, the necessity for subsequent trimming, as heretofore, being thus altogether obviated. It is to be understood, that the lugs 19 are so arranged on the chain 20 as to cause the switch 17 to be closed for current supply to the motor 15 just prior to the retraction of the yarn feeding finger.

Operation Incident to Yarn Introduction In FIG. 8, the finger 4 is shown in raised position with the yarn Y withdrawn. In FIG. 9, the finger 4 has been lowered to lay the yarn crosswise of the needle circle for feeding of the yarn to the needles, the first needle to take the yarn being designated 2". As the cylinder 1 rotates, the portion of the yarn still held by the movable clamp finger 32 is withdrawn from beneath the fixed clamp 30 and gradually dragged under the element 25 and thereby looped and thus tensioned about said element as shown in FIG. 10. By further rotation of the cylinder 1, the yarn, tensioned by restraining element 25, is eventually brought into the range of the rotary cutting wheel 8 and severed leaving but a short end projecting from the inside of the fabric in the same manner as above described during withdrawal of the yarn. Immediately thereafter the movable clamp finger 32 is raised as in FIG. 1 to release the isolated severed segment S of the yarn which is instantly sucked up through the pendent branch 43 of the tube 40, acting as an aspirator, and eventually blown into the catch basket 41 by the compressed air passing through tube 40. It is to be particularly noted from FIG. 1 that the end of the pendent branch 43 of the tube 40 reaches to a point below which the severed yarn segment S passes over the restraining element. As a consequence and due to the clearance between the overhanging portion of the restraining element 25 and the upper surface of the disk 5 the severed yarn segment S is removed Without difficulty.

Modified Embodiment of FIG. 12

In the embodiment of my invention illustrated in FIG. 12, the cutting wheel is driven by an air motor 15a interposed in the tube 40a, the exhaust from said motor creating the suction in the branch 43a of said tube. Since all of the other components of this embodiment of the invention are identical with those of the first described embodiment, in order to avoid the necessity for duplicate description, they are designated by the same reference numerals previously employed, with addition in each instance however of the letter a for convenience of more ready distinction.

Alternative Embodiment of FIGS. 13-15 In FIGS. 13, 14 and 15 which show an alternative means for removing the waste segments of the yarn after the severance during yarn changes, basal portion of the yarn restraining element 25b is provided with a small slot 45 and with a stop lug 46 adjacent to one end of said slot. As the yarn is drawn over the element 25b during withdrawal after the manner hereinbefore described in connection With FIGS. 4-7, it is arrested by the lug 46. In FIG. 13 the bracket 47 is secured by a screw 48 to a fixed part of the knitting machine which part may be the conventional cover 49 for the gears through which the usual dial for the welt transfer bits (not illustrated) is driven in unison with the needle cylinder 1. Rotatively borne in the bracket 47 is a shaft 50 to one end of which is secured a sheave 51, and to the other end of which is secured a ratchet wheel 52. As shown, the bracket 47 has a pendent extremity S3 with a lateral axis stud 54 at its lower end for a small sheave 55 which extends into the slot 45 of the yarn restraining element 25b. Adjustably secured to the bracket 47 adjacent the distal end thereof is a relatively short arm 56 on which are rotatively supported, an idler sheave 57 similar to the sheave 51, and a small sheave 58 of the same size as the sheave 55. Trained about the sheaves 51, 55, 57 and 58 is an endless spiral spring belt 60 which is flat sided in cross section as shown in FIG. 15 so as to be prevented from twisting in the grooves of said sheaves. The air tube 40b is provided, in this instance, with a nozzle 61 which directs its blast past the small sheave 58 and which is in line with the catch basket 41b, the tube and the basket being supported from the bracket 47 by hangers 62 and 63 respectively. The ratchet wheel 52 is arranged to be picked by pawl 65 on an arm 66 affixed to the shaft 50, said arm being connected by a link 67 to an arm 68 on a rock shaft 69 borne in a boss '70 on the bracket 47. The shaft 69 is arranged to be actuated through a linkage connection 71 from the conventional shear lever 72 of the knitting machine. By the means just described, it will be seen that the belt 60 is intermittently progressed and, as it passes about the small sheave 55, the convolutions thereof open up as in FIG. 14 to receive, following the lowering of yarn finger 4, the severed yarn segment S, which is caught and held between adjacent convolutions of the belt as the latter straightens immediately upon rounding said sheave. As the belt continues in its movement, the severed yarn segment S is drawn from beneath the element 25b in a manner readily understood from FIG. 13. The severed yarn segment S carried up by the belt 60 is released as the belt opens up in rounding the small sheave 58 and, upon being released, is blown into the catch basket 41b by the air blast released from the nozzle 61.

Modification of FIGS. 16-18 In the modification of FIGS. 16-18, the yarn restraining element 250 is identical to the element 25b of FIGS. 13 and 14 in that it is provided with a slot 450 and a stop lug 46c. The air tube 400 terminates in a nozzle 61c which, in this instance, is supported on a conventional cross bar 75 of the knitting machine, while the catch basket 410 is supported by a bracket 420 on the latch guard ring 3c. Pivoted at 76 on the upward projection 77 of the latch guard ring 30 is a lever 78 having, at the end of its longer arm, a pendent projection 79 which terminates in a hook 80. Guided on the projection 79 is a hook-closing slide or clamp 82 having a pin 83 extend- .ing outward through a slot 84 in said projection. As presently explained, the slide 82 is actuated at certain times by a yieldable spring finger 85 secured to the bar 75 by a screw 86, and at other times by a small lift finger 87 medially pivoted at 88 on the long arm of the lever 78. -A stop projection 89 is provided on the latch guard ring 3c to actuate the lift finger 87 as will also be presently explained. Supported by a bracket 90 on the upward projection 77 of the latch guard ring 30 is a cylinder 91 whereof the piston 92 is coupled, by a link 93, to the shorter or outer arm of the lever 78, the

upper end of said cylinder being connected at '94 to the air tube 400. interposed in the pipe 400 is a normally closed piston valve 95 of which the actuating stem is engaged by a pivoted finger 96 arranged to be operated through a thrust bar 97 from the usual main cam drum of the machine indicated at 98 in FIG. 17. Since the valve 95 is normally closed the piston 92 of the cylinder 91 will normally be raised by a spring 99 and, as a consequence, the lever 78 be normally held in the lowered position of FIG. 16.

Lever 78 is in its lowered position upon introduction of yarn Y to the needles after the manner hereinbefore described in connection with FIGS. 8-11, with the hook 80 open to receive the yarn Y as the latter is drawn beneath the yarn restraining element 250. Upon reception of the yarn within the book 8%, a rotary shift of the main cam drum 98 of the machine causes thrust bar 97 to be actuated upwardly by the action of the cam on the main cam drum. The upward action of thrust bar 97 against pivoted finger 96 opens valve 95 to permit compressed air to be admitted into cylinder 91, whereby the long arm of lever 78 is elevated as in FIG. 18. In its movement upward, the slide 82 is depressed by encounter of its stud 83 with the spring finger 85 with the result that the severed yarn segment S is effectively clamped in the hook 80 incident to be lifted through the slot 45c of the element 250. As the arm 78 nears the end of its upward stroke, the slide 82 is raised upon encounter of the tail of the finger 87 with the stop 89, the yarn segment S being thereby freed to be blown, by the air blast from the nozzle 610, into catch basket 410. By another rotary shift of the main cam drum 98, thrust bar 97 is lowered from the cam on the main drum to permit valve 95 to close, thereby removing the compressed air from cylinder 91, whereupon the spring 99 becomes effective to lower the arm 78 as in FIG. 16. During the downward movement of the arm 78, the slide 82 is lifted by encounter of its stud 83 with the spring finger 85 so that, upon eventual entry into the slot 45c of the yarn restraining element 250, the hook 80 will be open to receive the yarn Y as the latter is again drawn beneath the said element.

Having thus described my invention, I claim:

1. In a circular knitting machine having a rotary cylinder with a circle of independent needles, a dial cap mounted adjacent the top of said cylinder, at least one retractable yarn feed and yarn severing means disposed peripherally of said dial cap to sever yarn at a point angularly spaced from said yarn feed in the direction of cylinder rotation, a rigid yarn tensioning element mounted on the dial cap between the yarn feed and the point of yarn severance over which the yarn is drawn by rotation of the cylinder following each retraction of the yarn feed and about which, following each re-insertion of the yarn feed, the yarn is looped incident to being brought to the point of yarn severance by rotation of the cylinder, means for clamping and unclainping the yarn to the tensioning element and means disposed within the needle circle for removing severed yarn segments.

2. The invention of claim 1 wherein the yarn tensioning element is supported by the dial cap with intervening clearance therebetween, whereby following each reinsertion of the yarn feed the yarn is looped under said element to tension the yarn preparatory to severance thereof.

3. The invention of claim 1 wherein the yarn removal means comprises an aspirator.

4. The invention of claim 3 wherein the yarn severing means comprises two cooperative cutting devices, at least one of said devices being rotatable, an air motor for driving the rotatable cutting element and conduit means whereby the exhaust air from the motor comprises the air for the aspirator.

5. The invention of claim 1 wherein the yarn removal means comprises an endless belt adapted to transmit severed yarn segments to a yarn disposal point spaced 6 from the dial cap, and means for removing the'yarn segments from the belt.

6. The invention of claim 5 wherein the means for removing the yarn segments from the belt comprises a conduit having an open end disposed adjacent the yarn disposal point and means for causing air to flow through said open end.

7. The invention of claim 1 wherein the yarn removal means comprises a retractable clamp adapted to transmit severed yarn segments to a yarn disposal point spaced from the dial cap, and means for removing the yarn segments from the clamp.

8. The invention of claim 7 wherein the means for removing the yarn segments from the clamp comprises a conduit having an open end disposed adjacent the yarn disposal point and means for causing air to flow through said open end.

9. The invention of claim 7 further including means resiliently urging said clamp toward the dial cap and pneumatic means for retracting the clamp away from the dial cap.

10. In the operation of a circular knitting machine having a rotary cylinder with a complement of needles, a retractable yarn feed; and a clamp within the needle circle by which the end of the yarn is held while the feed is retracted, the steps of causing the yarn, upon insertion of the feed, to be formed into a loop about a fixed element adjacent the clamp within the needle circle; can-sing the yarn to be severed, upon completion of such loop, close to the first needle by which it was taken; thereupon causing the clamp to be actuated to release the cut loop; and finally applying suction at the bight of the out loop to remove the loop from about the fixed element within the needle circle.

11. In a circular knitting machine having a rotary cylinder with independent needles, a dial cap mounted adjacent the top of said cylinder, at least one retractable yarn feed and yarn severing means disposed peripherally of said dial cap to sever yarn at a point angularly spaced from said yarn feed in the direction of cylinder rotation, a conduit having an open end disposed above said dial cap at a point trailing said yarn feed and leading said yarn severing means in the direction of cylinder rotation, means for causing air to flow through said open end, a yarn clamp mounted above said dial cap between said yarn feed and said open end, means resiliently urging said clamp toward said dial cap, and pneumatic means for lifting said clamp away from said dial cap.

12. In a circular knitting machine having a rotary cylinder with independent needles, a dial cap mounted adjacent the top of said cylinder, at least one retractable yarn feed and yarn severing means disposed peripherally of said dial cap to sever yarn at a point angul-arly spaced from said yarn feed in the direction of cylinder rotation, a yarn clamp mounted above said dial cap between said yarn feed and said yarn severing means, means resiliently urging said clamp toward said dial cap and pneumatic means for lifting said clamp away from said dial cap.

13. In a circular knitting machine having a rotary cylinder with independent needles, a dial cap mounted adjacent the top of said cylinder and at least one retractable yarn feed, a conduit having an open end disposed above said dial cap at a point trailing said yarn feed in the direction of cylinder rotation, means for inducing air flow through said open end, a yarn clamp mounted above said dial cap between said yarn feed and said open end, means resiliently urging said clamp toward said dial cap and pneumatic means for lifting said clamp away from said dial cap.

References Cited in the file of this patent UNITED STATES PATENTS 1,086,570 Walker Feb. 10, 1914 (Other references on following page) 7 UNITED STATES PATENTS 2,713,254 Payne Mar. 5, 1929 3,006,173 Davis Jan. 13, 1942 Holmes ct al. J May 8, 194-5 7 Hilke: fit a1. July 15, 1947 6 749,044

' Minton July 19, 1955 Shoaf Oct. 31, 1961 FOREIGN PATENTS Great Britain ..7. May 16, 1956 

